Audio Visual Design Guidelines

Hardware Considerations

255 views November 22, 2018 November 19, 2019 aetm 0

Media Players

All digital signage systems require signage media players to present signage content.

Media players common features and considerations the current content playlist and schedule for playback to digital signage endpoint. They may be onboard a flat panel display, or a stand-alone device such as a PC or dedicated hardware device.

They may be integrated as part of a digital signage network Content Management System, or stand-alone onboard content management. They can also be integrated with a  building warning and alarm system/EWIS (Emergency Warning and Intercommunication System trigger).

The following features should be considered when selecting a media player:

  • use of an onboard hard drive, SD card slot, or USB port
  • Ethernet or WiFi network connectivity
  • digital video output (HDMI, DVI, Displayport, et al) to connect flat panel display or projector
  • audio output to speakers
  • general purpose input-output (GPIO) contact closure for remote trigger of content (ie Push button to start playlist “Welcome to Campus”)
  • serial control interface port (eg RS232) for automation control of flat panel display or projector
  • Universal Serial Bus (USB) interface port (interactive touch display, or keyboard & mouse)

It is also possible to deliver these features using a local PC or in some cases a flat panel display’s own on-board capabilities. If using the latter, it is important to consider that this may lock the organisation into a particular brand or model which may not be scalable or future proof.

When selecting hardware components it is important to understand how these features can be accessed by as well as access the digital signage platform of your organisation.

 

Display Types – Small to Medium Format Flat Panel Displays

All digital signage systems require displays to present signage content. Flat panel displays are the most common display type used for digital signage, and may be deployed indoors or outdoors.

Common digital signage applications for flat panel displays:

  • general information, messages, and advertising
  • kiosks (wayfinding, information directory, et al)
  • touch tables
  • interactive touch screen content
  • room booking and calendar information
  • menu-boards

Common considerations for flat panel displays would be to factor in if they need to:

  • be rated for continuous, uninterrupted 24/7 or 16/7 operation
  • have the manufacturer’s name and logo hidden
  • support mounting in portrait or landscape orientation
  • feature third party control capability (RS232, Ethernet / LAN)
  • feature an onboard digital signage media player

When considering your choice of flat panel display, there are three main technology options. LCD is the most widely available and the safest option for most applications, however both OLED and ePaper have specific niches where they can provide a better solution in certain environments.

 

LCD technology 

  • greater range of available image sizes 
  • flat image surfaces only
  • image quality satisfactory for digital signage applications
  • cost-effective display technology due to large market with many manufacturers

 

OLED technology

  • display technology susceptible to “burn-in”, always seek advice from manufacturer
  • more recent technology likely at a cost premium
  • flexible display surface options available (curved, flexible)
  • highest quality image contrast of all flat panel display technologies
  • smaller range of sizes and manufacturers

 

ePaper technology

  • ideal for semi-static, grey-scale content
  • only available in smaller image sizes
  • can be battery powered and standalone
  • can provide cost-saving through low power consumption and higher reliability
  • limited number of manufacturers and use-case scenarios

 

Video Wall Arrays

Multiple flat panel displays may be arranged together to make a video wall array. 

Common digital signage applications for video wall arrays are:

  • main entrances, atriums, and lobbies
  • menu-boards
  • exhibitions

When designing a video wall array the use of commercial grade flat panel displays specifically designed for this application is highly recommended. 

Features and considerations:

  • the thinner the bezel, the better the image (should be no more than 3mm)
  • a rating for 24/7 operation is optimal
  • will framerate synchronization be required
  • the ability for colour-balancing is essential
  • must feature third party control capability (RS232, Ethernet / LAN) and not rely on IR 
  • typically individual flat panel displays are in of a 16:9 format in the 40” to 60” size range

Be aware there is no standard composition for video wall equipment. Installation and design methods differ between manufacturers. Commonly standard video wall arrays are arranged symmetrically (eg, 2 x 2, 3 x 3) or to match an individual screen’s aspect ratio. They can also be completely flexible or freeform arrangements, although these will typically incur additional cost as they normally require the use of a dedicated video wall processor or windowing processor for flexible image orientation and positioning.

Standard format video wall arrays can generally be created much more cost-effectively, by utilising flat panel displays with onboard video wall features (including daisy-chaining, scaling, and framerate synchronisation).

It is very important to consider the bezel (area of real estate surrounding the screen surface) when selecting flat panel display for a video wall. 

Common bezel considerations are:

  • bezel size, as the gap between viewable images may impact readability and continuity of content across multiple displays
  • bezel compensation features, which may be employed to give the illusion that content is hidden behind the bezel, or continues on the adjacent pixels of the adjacent flat panel display
  • bezel designs that change colour to match the average hue of the signage content to hide the visual impact of the bezel are also available

A table giving which provides an example of standard video wall dimensions for 55” flat panel displays is available in the appendix.

Table – Standard Video Wall Arrays Dimensions – 55-inch

The below table is a reference and guideline for total estimated width and height of any given video wall array composed of 55-inch flat panel displays up to 6×6.

Rows/

Columns

1 2 3 4 5 6
1 W 1215mm

H 685mm 

W 2430mm, H 685mm  W 3645mm, H 685mm  W 4860mm, H 685mm  W 6075mm, H 685mm  W 7290mm, H 685mm 
2 W 1215mm, H 1370mm  W 2430mm, H 1370mm  W 3645mm, H 1370mm  W 4860mm, H 1370mm  W 6075mm, H 1370mm  W 7290mm, H 1370mm 
3 W 1215mm, H 2055mm  W 2430mm, H 2055mm  W 3645mm, H 2055mm  W 4860mm, H 2055mm  W 6075mm, H 2055mm  W 7290mm, H 2055mm 
4 W 1215mm, H 2740mm  W 2430mm, H 2740mm  W 3645mm, H 2740mm  W 4860mm, H 2740mm  W 6075mm, H 2740mm  W 7290mm, H 2740mm 
5 W 1215mm, H 3425mm  W 2430mm, H 3425mm  W 3645mm, H 3425mm  W 4860mm, H 3425mm  W 6075mm, H 3425mm  W 7290mm, H 3425mm 
6 W 1215mm, H 4110mm  W 2430mm, H 4110mm  W 3645mm, H 4110mm  W 4860mm, H 4110mm  W 6075mm, H 4110mm  W 7290mm, H 4110mm 

 

LED Video Walls

Light-Emitting Diode (LED) display technology is commonly used for large-format (10sqm and greater) display surfaces, and may be deployed indoors or outdoors.

LED video walls are designed and built to the project requirements. While there is great variance of methods and technology among LED manufacturers, there are some common-place guidelines that can be employed during the planning phase.

Common digital signage applications for LED video walls:

  • Main entrances, atriums, and lobbies
  • Roadside signage
  • Building facade signage

Typically LED video walls are composed of individual panels enclosed in a display cabinet or mounting system installed at signage display location; with the controller, power supply, a video scaler/processor installed within an equipment rack. The digital signage media player or computer can be placed in either location, although commonly some form of local input is also desirable.

An LED video wall is an array of physical pixels (LEDs) that represent individual pixels of digital images, text, and video. As such, often LED video wall resolutions don’t match standard display resolutions (720p, 1080p, WXGA, et al) and this can cause undesirable effects in the displayed content (blank borders, pillarboxing, letterboxing, etc).

If the video wall is mounted to a wall or bulkhead surface, it is highly desirable that the system is front-serviceable. Otherwise the entire wall must be lowered or removed to effect repairs. Sometimes this is preferable (such as when mounted at a height) and in these situations a winch system is a better option.

It is important to be aware that an image is downscaled if the number of LEDs is less than the number of pixels in the digital source image. This may be especially impactful to the readability of text and detailed content.

 

Pixel pitch is the distance between LED physical pixels. The ideal pixel pitch is determined by the minimum intended viewing distance, using the calculation:

P = D x 2

P is the recommended pixel pitch in millimetres (mm)

D is  the minimum intended viewing distance in metres (m)

Example: If minimum viewing distance is 6m, the recommended pixel pitch is 3mm

 

The total resolution of a LED video wall can be simply calculated using the following formula:

 = (W / P) * (H / P) L

L is the LED video wall resolution (total number of LEDs)

W is the video wall surface width millimetres (mm)

H is the video wall surface height millimetres (mm)

P is the pixel pitch in millimetres (mm)

Example: If the video wall dimensions are 3840mm x 2880mm and the pixel pitch is 3.5mm, the resolution is 1097 x 822 (902,792 pixels, close to 720p image)

 

Commonly LED video walls can produce images with a luminance brightness of between 2,000 to 14,000 Nits. The brightness of the LED video wall should be adjusted accordingly to the ambient lux of the signage location and time of day.

It is also worth noting that LED street lighting and outdoor video walls are the primary cause of light pollution worldwide, and it is important not to contribute to this effect. As such the LED video wall should either be set to the minimum available brightness during night-time operation (typically 1-5%) or preferably have an automatic adjustment system based on ambient light conditions. This will give the best performance under all conditions, and prevent the image being too bright for comfortable viewing on overcast days.

 

Display Types – Projection

Projection is commonly used for large-format (5sqm and greater) signage applications, and may be deployed indoors or outdoors.

Common digital signage applications for projection:

  • Main entrances, atriums, and lobbies
  • On floor signage
  • On ceiling signage
  • Building facade signage and projection mapping

Projection systems have more flexibility for installation than other signage display types, as they are not restricted to a flat display surface and can ustilise either front or rear projection. They may be projected onto the floor, ceiling, stairs, and other non-flat or non-vertical surfaces. Mirrors can also be utilised to hide the projector and other equipment, as the image may be reflected onto the display surface at any point in the light path.

However, it is very important to note that projected images are more susceptible to the impacts of natural light, and may look washed-out or faded in areas exposed to high ambient light levels. The amount of contrast in an image is always determined by the black level. Where there are high levels of ambient light present, no matter how bright the projector is, the image quality will still be poor. 

The best strategies to improve the image quality is always to reduce the ambient light on the display area, however it may also be possible to use a high gain or specialist screen to mitigate the effect. Alternatively consider a different technology such as LED.

There is no recommended brightness that a projected image should achieve specifically in relation to digital signage, as this will entirely depend on the individual use-case scenario. However, a tool to calculate the estimated brightness can be found in the appendix.

 

Estimated Lux and Nits of a projected image is calculated as follows:

    • Given S is the projected image surface area in square metres (sqm)
    • Given L is the projector ansi lumens rating in
    • Given X is the projected image illuminance in Lux
    • Given N is the projected image luminance in Nits
    • X = L / S
    • N = X / 3.14

Example: With a 8,000 lumens projector producing a projected image of 4.65sqm (130” 16:9), the resulting illuminance is 1,720 Lux and luminance is 547 Nits

 

Projector Stacking

Projector stacking is a projection technique whereby two or more projectors are combined to create the same projected image. 

This technique can be used to counter the issue of blocked light paths, one of the disadvantages of projection. Shadows created by the light path being interrupted (for example by objects or people) may be mitigated by projecting onto the display surface from multiple angles. Commonly this would require the use of more than two projectors, or the shadow will still be obvious.

The brightness of a projection image may be greatly increased by multi-stacking projectors. The resulting brightness is the sum of all projected images produced by the projectors. This also provides a level of redundancy if one projector fails. However, one important disadvantage of projector stacking is that it may be prone to image alignment issues which will significantly impair the image quality. 

As such, projector stacking should only be used where there is zero risk of any movement in either the projector or display surface. 

 

Edge-Blended Projection

Edge-blending is where the projected image is expanded across multiple projectors (similar to a video wall array). It is an image processing technique that softens (feathers) the overlapping edges of projected images to give the illusion of a seamless large projected image.

Edge-blending may be achieved by using software to create content with overlap zones. Alternatively hardware such as a video wall processor or an onboard projector feature can be used. It is important to consider the light path from the projector lens to the display surface and any obstructions that block the light path should be avoided or removed.

Be aware that even when perfect edge-blending has been achieved at the point of installation, it is very common for this to degrade over time and your installation may not achieve a pleasing image over the desired life cycle. Regular calibration should be factored in, plus early and ongoing engagement with the manufacturer or integrator is essential.

 

Weather and Environmental Exposure

If the signage endpoint is located partially outdoors or exposed to weather and environmental impacts in anyway the following measures may be employed:

  • the digital signage equipment should itself be rated to IP66 or housed within an IP66 rated enclosure to protect from dust and water (or certain components could be located in a nearby building)
  • power and data outlets must be protected within an IP66 rated enclosure to protect from dust and water
  • all equipment shall be rated IP51 as a minimum
  • operating temperatures must be within the warrantable operational temperature range stated by the manufacturer(s)
  • Where possible, equipment shall be covered by warranty if subject to damage from weather and environmental effects for the life-cycle of the installation

 

Natural Light and Image Brightness

If the signage endpoint is located in an area exposed to natural light the following measures may be employed:

  • Avoid projection systems, unless the use-case is well suited and natural light exposure can be mitigated to support the required contrast ratio
  • Install awnings, shrouds or other shade structures to avoid sunlight impacting the digital signage equipment or viewable image
  • Instead of projection, deploy high-brightness flat panel displays (800 Nits or greater)
  • Deploy LED video walls with standard high brightness (2,000 to 14,000 Nits)
  • Avoid installation of digital signage equipment where it may be exposed to direct sunlight, or employ mitigation strategies to ensure manufacturer is satisfied and will maintain their equipment warranty
  • Avoid positioning digital signage endpoints where sunlight directly shines on, or reflects onto the viewable image surface
  • If none of the above can be achieved, consider an alternative location for the digital signage endpoint

 

Mounting, Enclosures, Environment, and Locations

Digital signage endpoints are commonly installed in areas accessible to the general public. The integrity and security of the mounting and enclosures is vital to mitigate risks of injury, vandalism, and damage to structures or equipment.

Some common best-practice and considerations for digital signage location, mounting and enclosures include:

  • coordinate with internal building teams to ensure sign-off is granted (if required) for any installation that is public-facing
  • calculate the total weight of all digital signage endpoints (display, brackets, digital signage media players), ensuring the structure can support the weight of the installation. These numbers must be provided to building services teams due to the importance of safety of staff, students and the public.
  • viewing requirements for digital signage can be more relaxed compared to viewing within teaching and meeting spaces. The application and related content should lead to a common-sense decision on what is appropriate for viewing distance and viewing angles: 
    • where text-based information is critical, AVIXA’s DISCAS calculator for Basic Decision Making (BDM) should be used to determine the appropriate parameters
    • where information is less critical, or designed to draw the intended audience closer to a defined area from which they can read, the “Passive Viewing” category should be used for calculating screen sizing
  • ensuring the digital signage endpoint is installed in a location that is not obstructed by other building elements when viewed from the primary intended audience location. e.g. the viewing path from the entrance of a foyer is not obstructed by a column, or a display viewed through an external window is aligned to avoid mullions
  • ensuring all digital signage media players, cabling, and accessories are fixed in place and hidden from view
  • touch-interactive portion of the content must be at heights between 900mm and 1200mm above finished floor level, or adhere to organisational and project DDA (Disability Discrimination Act) standard mounting heights
  • touch-interactive digital signage endpoints must not have any obstructions directly in front of the display that may block wheelchair access
  • the digital signage endpoint including any mounting and enclosures must not obstruct the path of travel
  • If the digital signage endpoint is located in an area accessible to the general public, consider the following measures:
    • Install equipment at 2.5m or higher to allow for persons passing under on personal vehicles (bicycles, scooters, skateboards etc.)
    • Install equipment within vandal-proof or protective enclosure if required
    • Install remote-monitoring components such as IP cameras, tamper sensors and alarms, if required
  • Consider the environment where the digital signage endpoint is installed:
    • the temperature should remain constant
    • the humidity should remain constant
    • avoid installation locations where any vibrations caused by vehicles, foot traffic, or equipment may damage digital signage equipment
    • air quality should be free of any dust that may impact the equipment performance
    • the digital signage endpoint should not be exposed to direct sunlight
    • where the above environmental factors can not be overcome by location or enclosure selection, investigate alternative products specifically designed to work in the specific environmental conditions of the digital signage location
  • Wall mounted signage endpoints should:
    • ensure the wall is structurally sound for the wall mounted components, Installing structural reinforcement if necessary
    • ensure the mounting brackets and hardware are rated for the size and weight of the display
    • use tilt or articulating arm brackets to angle the display towards the intended viewing position / zone
    • ensure maintenance requirements are considered and agreed upon with local support teams, including mounting points for media players and brackets that allow service positioning
    • if the digital signage display is installed into a wall recess, ensure the recess is of sufficiently sized in accordance with manufacturer’s requirements for ventilation purposes. When in doubt, contact the manufacturer and request in writing confirmation of warranty. This can be deferred to an architect or builder who may have specific aesthetic goals
  • Ceiling mounted signage endpoints should:
    • when installing mounting hardware to concrete sofit, ensure all penetrations and anchor points are coordinated with the building structural engineer
    • when installing mounting hardware onto truss, or other structural elements, ensure those elements will support the total weight of the digital signage endpoint components
    • ensure the mounting brackets and hardware are rated for the size and weight of the display
    • angle the display towards the intended viewing position/zone
    • consider fixing a back box to hide any cabling and devices if the back of the display is visible and prominent
  • Floor standing enclosures (ie kiosks and touch tables):
    • ensure the enclosure and base plate is fixed to the floor surface and will not topple if pushed or if someone leans against it
    • ensure the enclosure has sufficient ventilation to avoid overheating
  • Embedded displays (lifts, vending machines, furniture):
    • ensure the enclosure has sufficient ventilation to avoid overheating

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